The following background discussion includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
Wheeled vehicles (e.g., trucks, cars, etc.) secure wheels to an axel via a rim held in place by a plurality of nuts. During a normal course of traveling, the nuts can progressively loosen to the point where the wheel is no longer properly secured typically as a result of heat transfer, often through braking where expansion and contraction of the stud bolts occurs. As the stud bolts lengthen the nut torque pressure becomes reduced allowing the nut to loosen and centrifugal force to undo the nut. In some scenarios, the wheel can detach from the vehicle during travel resulting in a severe safety hazard. There exist numerous documented cases of bystanders being severely injured or dying as a result of detached wheels.
United States Patent Application Pub. No. 2002/0122711 to Porter titled “Wheel nut retainer,” filed on Mar. 2, 2001 attempts to resolve these issues and describes a retainer for securing a truck wheel nut to a rim clamp of a wheel to prevent the wheel nut from turning relative to the rim clamp. Unfortunately, the device of Porter can only be secured to a truck wheel. Moreover, a separate device would need to be attached to each wheel nut and Porter does not provide an indicator to signal loosening of a wheel nut. A more desirable solution would be a device that works on more than one wheel nut and indicates that the nut is loose.
International Application WO 2007/090986 to De Lima titled “Safety device for vehicle wheel,” filed on Feb. 5, 2007 and United Kingdom Patent Application GB 2325504 to Rowledge titled “Device to prevent loosening of wheel nuts,” filed on Dec. 29, 1997 attempt to address these issues and describe safety devices for vehicles that include retention walls to prevent the complete loosening of wheel nuts. De Lima provides an anti-rotation means designed to co-operate with the wheel nuts. Rowledge provides a ring member with a retaining rim. Unfortunately, the devices of De Lima and Rowledge do not include nut caps to protect the wheel nuts from debris and dust, or internal ribs for structural support to reduce the flexibility of the devices. More significantly, they do not provide any easily identifiable indicators to signal the loosening of the wheel nut to the vehicle operator. A more desirable solution would include such an indicator.
Canada Patent Application CA 2206849 to Keenan titled “Truck wheel retaining device and alarm system,” filed on Jun. 3, 1997 attempts to resolve such issues and discloses a system that provides an alarm to warn the vehicle operator of a loose wheel. While Keenan provides electronic signals to vehicle operator when a wheel is loose, it does not provide external validation for inspectors walking around the car. Moreover, the wiring of the system is complex and cannot be easily installed by the vehicle operator. Perhaps most significantly, Keenan fails to send electronic signals upon the loosening of individual wheel nuts.
Yet another example is United Kingdom Patent GB 2393487 to Knight titled “Wheel nut indicator and retention device”, filed Aug. 29, 2002. The disclosed approach by Knight provides an exposed indicator of a loosening wheel. However, Knight's device is made of polypropylene, and also fails to send electronic signals upon the loosening of individual wheel nuts.
Unless the context dictates the contrary, all ranges set forth herein should be interpreted as being inclusive of their endpoints and open-ended ranges should be interpreted to include only commercially practical values. Similarly, all lists of values should be considered as inclusive of intermediate values unless the context indicates the contrary.
What the above references fail to provide is a system that can be easily installed and understood by an average vehicle operator, include a signal upon the loosening of individual wheel nuts, and provide external validation for inspectors. Thus, there is still a need for improved nut sensing devices.